Organopolysiloxane has so far been used as additive or modifier with an intention of imparting various useful functions to paint and varnish. On the other hand, study of silicone type graft copolymers prepared utilizing silicone monomers on the basis of the recent advancement in macromonomer technique have been made extensively. These copolymers have absorbed much interest as a coating material excellent in weather resistance, water repellability, stain resistance, mold releasability, lubricity, and so on [as disclosed in Japanese Kokai Nos. 154766/58, 20360/59, 126478/59, 151272/61 and 156172/62 (The term "Japanese Kokai" as used herein means an "unexamined published Japanese patent application")].
However, all of those graft copolymers are prepared from a radical polymerizable group-containing organopolysiloxane and radical polymerizable monomer(s). More specifically, their major component is a graft copolymer which contains organopolysiloxane as the branch component and an acrylic polymer as the trunk component.
Consequently, when the trunk polymer has a high glass transition point, the coat obtained is hard and excellent in thermal resistance, on the one hand, but fragile and devoid of flexibility on the other hand. Therefore, when it is designed so as to have a low glass transition point with the intention of heightening the flexibility, the coat formed becomes tacky and soft. That is, conventional silicone type graft copolymers have a defect that they cannot provide a satisfactory coat.
As a result of concentrating our energies on elimination of the above-described defect, it has now been found that a coating composition whose major component is a graft copolymer containing both organopolysiloxane and polylactone as branch components is excellent in not only weather resistance, water repellability, stain resistance, mold releasability and lubricity, but also flexibility and impact resistance, so it is best suited to be used as a weather resisting coating material for construction use, a coating material for preventing water and snow from adhering, a coating material for protection from patching paper and scribbling, a coating material for protection from sea water stains, a water proof coating material for concrete, a coating agent for backing ink ribbon used for heat-sensitive transfer recording, a coating agent for backing magnetic tapes, and so on, thus achieving this invention.